Guide to using High Temperature Silicone Sealants

High temperature silicone sealants are special adhesives or glues formulated for applications in elevated temperature.

As the name suggests, these sealants are made from silicone materials, alongside other additives.

In this article, we shall explores critical variables about these special adhesives.

Advantages of Heat Resistant Silicone Sealant

Heat Resistant Silicone Sealant
Heat Resistant Silicone Sealant

Conventional sealants simply cannot withstand the extreme demands of industrial applications involving high heat. If you opt for these sealants, you will benefit from:

  • Heat Resistance – These sealants consistently can resist extended exposure to temperatures ranging from 300°F to 500°F.
  • Superior Adhesion–They maintain adhesive properties at elevated temperature as long as it is within the working limits.
  • Weatherability – In addition to heat, it can also endure severe weathering from UV exposure, moisture, and daily thermal cycling with no visible cracks or loss of elasticity.
  • Low Smoke & Toxicity – Many varieties meet stringent industrial safety standards with negligible smoke or toxicity should exposed to high heat, such as during a structure fire.
  • Flexibility – Remains flexible over a wide temperature range, absorbing thermal expansion and contraction stresses rather than cracking or becoming brittle.
  • Excellent Gap-Filling – Silicone polymers flow easily into crevices and spaces, creating an airtight barrier against air, water, dust, and fire. Gaps up to 1/2 inch can often be filled.

Types of Temperature Silicone Sealants

In most cases, we classify these sealants depending on their temperature range.

Depending on your applications, you can choose:

  • 300°F Sealants – Suitable for surfaces maintaining temperatures up to 300°F, including ovens, bakeware, and automobile manifolds.
  • 400°F Sealants – Ideal for settings ranging from 300 to 400°F such industrial machinery, motors, boilers, and kitchen equipment.
  • 500°F Sealants–Even at 500°F, it will still guarantee perfect sealing.
  • 600°F Sealants – Usually, we use these in higher temperature applications such as jet engines.

Every category also has single- or multi-component variations. While two-part versions entail premixing a base compound and catalyst, 100% silicone sealants are often one-part and ready-to-use right from the tube.

Silicone Sealant Temperature Range

Silicone sealant temperature range that is typically 100-150°F lower than their rated maximum. It’s usually best you stay within 80-90% of the stated temperature rating for optimal sealant longevity.

Special high-heat varieties are also available with continuous usability up to 3000°F for the most severe industrial applications.

Remember, your manufacturer will specify the recommended temperature range of each product.

Molecular Structure of Silicone Sealants
Molecular Structure of Silicone Sealants

How to use High Temp Silicone Sealants

Using high temperature silicone is straightforward. In fact, most manufacturers indicate on their product how to apply this silicone.  Well, the process is simple and straight forward, it involves:

  • Clean and dry all surfaces completely, then eliminate any trash, oil, grease or other leftovers. One could find assistance with an alcohol wipe.
  • Applying a primer might be required to increase the bonding strength of sealant on non-porous materials such as glass and metal. Check manufacturer recommendations.
  • Cut the tip off the cartridge or nozzle to the required bead size, then rupture the inside seal. Use a suitable caulking gun.
  • Pressing the bead or fillet into any cracks or gaps, apply the sealant with constant pressure.
  • Tool the sealant towards the substrate from the centre outward on vertical joins.
  • Apply in a constant spiral motion for an uninterrupted watertight closure if sealing tubing.
  • Let suggested cure times run before exposing to water or service temperatures.
  • Apply an equal quantity or amount of sealant to both surfaces then press firmly together while curing for bonding purposes. As necessary, use weight or clamp.

Key Applications

Applying Silicone on Engine
Applying Silicone on Engine

You can use these sealants in:

  • Wood sections – these may include fences, floor sections, walls, decks, etc.
  • Metallic sections – from heat exchanger systems, ductwork, roofing, automotive exhaust, manifolds, to furnace, these sealants are perfect for any job.
  • Glass surfaces – whether you are using insulated glass, glass-ceramic, mirrors or glass cooktops, you can consider silicone sealants.

Apart from these, you can also use temperature resistant silicone sealants on barbecues, chimneys, stoves, ovens, outdoor grills, asphalt roof seams, stucco joints, and more


Which Silicone Sealant is best for High Temperature use?

First, you should go for one with temperature ranging from 400°F to 450°F and higher would be advised. Look for 100% RTV silicone formulations without fillers or additives that could compromise the sealant under extreme conditions.

What is the Maximum Temperature for High Temp Silicone?

The highest rated construction grade sealants can maintain integrity from -80°F to well above 500°F in intermittent heat, with some exceeding 1,000°F or more for short durations. The true maximum continuous use temperature generally lies 100-150°F below the stated rating.

How long will it Take High Temperature Silicone to Cure?

Full cure with maximum bonding and strength typically requires 24 to 48 hours depending on conditions, with thicker applications taking longer. At minimum, allow 24 hours before exposing new sealants to water or high heat.


For many years, silicone based sealants remain popular options for high temperature applications. This is mainly attributed to silicone high temperature resistance.

At LEGENDAY, we help you get the best silicone products depending on your unique application requirements. For any inquiries, contact us now.

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